Training: Suggestion 2 from @melgor in #48.

training/train.lua

@@ -149,6 +149,7 @@ function trainBatch(inputsThread, numPerClassThread)
    local tripIdx = 1
    local shuffle = torch.randperm(numTrips)
    local embStartIdx = 1
+   local nRandomNegs = 0
    for i = 1,opt.peoplePerBatch do
       local n = numPerClass[i]
       for j = 1,n-1 do
@@ -166,16 +167,23 @@ function trainBatch(inputsThread, numPerClassThread)
             selNegIdx = (torch.random() % numImages) + 1
          end
          local selNegDist = dist(embeddings[aIdx], embeddings[selNegIdx])
+         local randomNeg = true
          for k = 1,numImages do
             if k < embStartIdx or k > embStartIdx+n-1 then
                local negDist = dist(embeddings[aIdx], embeddings[k])
-               if posDist < negDist and negDist < selNegDist and
-                    math.abs(posDist - negDist) < alpha then
+               if posDist < negDist and negDist < selNegDist then
+                  randomNeg = false
                   selNegDist = negDist
                   selNegIdx = k
+                  if math.abs(posDist-negDist) < alpha then
+                    break
+                  end
                end
             end
          end
+         if randomNeg then
+            nRandomNegs = nRandomNegs + 1
+         end
 
          ns[shuffle[tripIdx]] = inputsCPU[selNegIdx]
 
@@ -185,6 +193,7 @@ function trainBatch(inputsThread, numPerClassThread)
    end
    assert(embStartIdx - 1 == numImages)
    assert(tripIdx - 1 == numTrips)
+   print(('  + (nRandomNegs, nTrips) = (%d, %d)'):format(nRandomNegs, numTrips))
 
 
    local beginIdx = 1